Investigation of phytochemical and morphological response of a local Cyamopsis tetragonoloba L. mass to foliar application of zinc oxide nanoparticles

Since supplementation of plants with zinc is a solution to improve plant growth and compensate for zinc deficiency in soil, in this study to investigate the nutritional effect of 40 nm zinc oxide nanoparticles (ZnO-NPs) on morphological characteristics, seed gum and phytochemical products of leaves of a native mass of Cyamopsis tetragonoloba L (Gguar plant) from Iranshahr a completely randomized experiment with three replicates was conducted at the University of Sistan and Baluchestan, Zahedan, Iran in mid-May 2018. Guar gum content, total phenol content and total flavonoid content were determined by the phenol-sulfuric acid, the Folin–Ciocalteu reagent, and colorimetric aluminum chloride methods, respectively. Seed cultivation was carried out in the greenhouse of Sistan and Baluchestan University in early June 2018. The treatments consisted of six different concentrations of ZnO-NPs including 0 (control), 25, 50, 100, 200, and 500 mg L-1 by foliar application of guar plants in two stages (20 and 27 days after sowing seeds). Based on the results, with increasing the concentration of nanoparticles, the number of seeds in pod gradually decreased, but no significant difference was observed in pod length and root length. However, stem length, stem dry weight, root dry weight, leaf area, stomata density, leaf dry weight, 500-seed weight, pod dry weight gradually increased, with the maximum increase observed in the 500 mg L-1 treatment compared to the control. In this treatment, seed gum, total phenol and total flavonoids increased by 2.55, 2.10 and 1.34 times compared to the control treatment, respectively. According to the results, ZnO-NPs nanoparticles with the properties used in this study can be used to improve the growth characteristics and increase the amount of seed gum, phenol and flavonoids of guava leaves and obtain the benefits of their medicinal applications.